1. The number of prime factors in the expression 25x26x36x53:

2. Reduce 391/667 to lowest terms:

3. If H.C. F of two numbers is 7 and their L.C.M is 210. And If one of the numbers is 35, find the other:

4. There are 2 numbers such that a > b, HCF (a, b) = h and LCM (a, b) = l. What is the LCM of axb and a/b?

5. There are 2 numbers such that a > b, HCF (a, b) = h and LCM (a, b) = l. What is the LCM of a+b and a-b?

6. Find the H.C.F of 108, 360 and 600.

7. The traffic lights at three different road crossings change after every 48 seconds,72 seconds and 108 seconds respectively .If they all change together at 8:20:00 hours,then at what time they would again change together .

8. Find the least number which when divided by 5,6,7, and 8 leaves a remainder 3, but when divided by 9 leaves no remainder .

9. Find the H.C.F of 204, 1190 and 1445:

10. Three big drums contain 36 litres, 45 litres and 72 litres of oil. What is the biggest measure that can be used to measure all the different quantities exactly?

11. A red light flashes 3 times per minute and a Green light flashes 5 times in two minutes at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?

12. What is the greatest length possible of a scale that can be used to measure exactly 3m , 5m 10 cm and 12m 90 cm length?

13. H.C.F and L.C.M of two numbers x and y are 3 and 60 respectively. If x+y=18 then figure out 1/x + 1/y .

14. Find the greatest number which divides 62, 132 and 237 leaving the same remainder in each case.

15. What is the minimum number of square bricks required to make a floor of length 5 metres 78 cm and width 3 metres 74 cm?

16. A call centre observes that it gets a call at an interval of 10 minutes from Kolkata, at every 12 minutes from Mumbai, at the interval of 20 minutes from Delhi and after interval 25 minutes it gets the call from Chennai. If in the early morning at 5:00 a.m. it receives calls from all the four cities, then at which time it will receive the calls at a time from all places on the same day?

17. Find the L.C.M of 2/3 , 8/9 , 10/27 and 16/81:

18. The LCM of two numbers is 280 and their ratio is 7:8. The two numbers are

19. Two numbers are in the ratio 8:11 . Considering their H.C.f as 6, find the numbers:

20. The H.C.F of 1/2 , 2/3 , 3/4 , 4/5 is:

21. Find the H.C.F of 108, 288, and 360:

22. Four electronic devices make a beep after duration of 30 minutes, 1 hour, 3/2 hours and 1 hour 45 min. respectively. If all the devices beeped together at 12 noon at what time will they beep together again?

23. The sum of two numbers is 75 and their difference is 1/5th of their sum. What is their L.C.M:

24. Find the greatest number which can exactly divide 513, 783 and 1107 leaving same remainder.

25. The least number which should be added to 2497 so that the sum is exactly divisible by 5,6,4 and 3 is: